/***********************************************************
 
 File name: UIColor+Hex.m
 Author:    xuwei
 Description:
 颜色用字符串表示
 
 History:
 2018/02/27: Created
 
 ************************************************************/

#import "UIColor+Hex.h"

@implementation UIColor (Hex)

/**
 字符串转化为颜色

 @param color 颜色字符串
 @param alpha 透明度
 @return UIColor
 */
+ (UIColor *)colorWithHexString:(NSString *)color alpha:(CGFloat)alpha {
    NSString *cString = [[color stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] uppercaseString];
    
    // String should be 6 or 8 characters
    if ([cString length] < 6) return [UIColor whiteColor];
    
    // strip 0X if it appears
    //如果是0x开头的，那么截取字符串，字符串从索引为2的位置开始，一直到末尾

    if ([cString hasPrefix:@"0X"]) cString = [cString substringFromIndex:2];
    //如果是#开头的，那么截取字符串，字符串从索引为1的位置开始，一直到末尾
    if ([cString hasPrefix:@"#"]) cString = [cString substringFromIndex:1];
    if ([cString length] != 6) return [UIColor whiteColor];
    // Separate into r, g, b substrings
    NSRange range;
    range.location = 0;
    range.length = 2;
    //r
    NSString *rString = [cString substringWithRange:range];
    //g
    range.location = 2;
    NSString *gString = [cString substringWithRange:range];
    //b
    range.location = 4;
    NSString *bString = [cString substringWithRange:range];
    
    // Scan values
    unsigned int r, g, b;
    //把指定的range的子串取出来（应该是16进制格式的），转成10进制整数存到r/g/b变量里
    [[NSScanner scannerWithString:rString] scanHexInt:&r];
    [[NSScanner scannerWithString:gString] scanHexInt:&g];
    [[NSScanner scannerWithString:bString] scanHexInt:&b];
    
    return [UIColor colorWithRed:((float) r / 255.0f)
                           green:((float) g / 255.0f)
                            blue:((float) b / 255.0f)
                           alpha:alpha];
}

/**
 字符串转化为颜色（默认alpha值为1）

 @param color 颜色字符串
 @return UIColor
 */
+ (UIColor *)colorWithHexString:(NSString *)color {
    return [self colorWithHexString:color alpha:1.0f];
}

@end
